Benign epithelioid peripheral nerve sheath tumour resembling schwannoma

Peripheral nerve sheath tumours (PNST) with epithelial appearing cells compromise a heterogeneous group of neoplasms that are rare and diagnostically challenging. Of these, malignant PNSTs with epithelioid features (epithelioid MPNST) are commonly described in literature. However benign epithelioid PNSTs are rare and till date about 38 cases have been described in the literature. We report a benign epithelioid PNST with light microscopical and immunohistochemical features suggestive of schwannoma, presenting as a thigh mass in a 23-year-old female. The tumour was encapsulated, showed epithelioid cells in aggregates, and expressed vimentin and S-100 positivity. There was no expression of CD34, CK, EMA, CD99, p63 and HMB 45. Typical Antoni A and Antoni B areas were absent. At 18 months follow-up, the patient was well.